This gist is used in the tutorial https://www.vijayan.in/how-to-create-custom-table-list-in-wordpress-admin-page

allowed_post_types_readable.php

<?php
...
	/**
	 * A map method return all allowed post types to human readable format.
	 *
	 * @return array Array of allowed post types in human readable format.
	 */
	private function allowed_post_types_readable() {
		$formatted = array_map(
			array( $this, 'human_readable' ),
			$this->allowed_post_types
		);

		return $formatted;
	}
...